The GMDSS enables Maritime Rescue Centres and radio stations to keep automatic watch on the
distress channels. A ship equipped with a DSC apparatus can make a distress call by simply
pressing a button, which results in an automatic alarm signal at the maritime rescue centre nearest
to the vessel.
DSC can be used for all kinds of radio calls between ship-ship and ship-shore–ship. DSC calls are
made on channel 70, which means that any voice communication on this channel is not allowed.
The DSC call includes and shows the following information:
- Format or Type of Call
- Receiver or Party ID
- Call Category or Priority
- Telecommand
(follow-up radio communication)
- Working Channel
1. FORMAT OR TYPE OF CALL
One of the following are chosen on the DSC apparatus:
- distress alert / distress call in a distress
- all ships a call to all stations
- selective/individual a call to one station
(e.g. in routine calls)
- group a group of stations
- area / geographical call to stations in a
particular area
2. PARTY/RECEIVER ID (IDENTIFICATION)
The receiver of the call (Party ID) you can click either the Maritime Mobile Service Identity (MMSI)
number of the recediving station, a group call number or area call number. The MMSI always
contains nine digits.
Example of MMSI Number system:
MMSI Vessel Explanation
230252000 230 country code (Finland)
always three digits
252000 (ship’s number)
MMSI Coast Station Explanation
002301000 00 means coast station in general
230 country code (Finland)
number of particular coast station
1000 (Turku Maritime Rescue Coordination Centre)
3. CALL CATEGORY OR PRIORITY
- distress
- urgency
- safety
Routine Communication can be of two kinds:
- routine
- ship’s business
4. TELECOMMAND
This gives information on what kind of follow-up radio communication the sender wishes to have. It
also gives information on what kind of message the sender is giving. The most common
telecommand choices include:
- telephony G3E/F3E simplex
o voice communication on VHF
- distress acknowledgement
o request for acknowledgement of distress call
- distress relay alert
o request for relay of distress
- ship’s position
o request for a vessel’s position to be shown on DSC (routine call)
5. WORKING CHANNEL
The one who sends a DSC call can suggest a working channel for continued voice radio
communication.
NOTE: When a vessel is calling a coast station it does not suggest a working channel. The coast
station announces which radio channel to continue on.
ROUTINE COMMUNICATION WITH DSC CALL
EXAMPLE 1
A RADIO MESSAGE FOR SUOMENLINNA COAST GUARD STATION
COMPARE THE FOLLOWING TO THE EXAMPLES SENT WITHOUT DSC:
A Russian yacht Marlene is approaching the Finnish coast on its way to spend a holiday partly in
Helsinki and partly by sailing in the Finnish archipelago. According to European union laws a
foreign pleasure boat must report for passport control when she has entered the territorial waters
of one of the member states. The Marlene is a luxury yacht and is linked to GMDSS and has DSC.
It is 12.30 at Suomenlinna Coast Guard Station on a fine summer day.
The DSC at Suomenlinna starts signalling and shows the following message:
Format: SELECTIVE
Party ID: 002300005
Category ROUTINE
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70
NOTE: Marlene does not suggest a working channel. In communication between ship and coast
station, it is always the coast station that determines the choice of working channel.
SELECTIVE directed to a specific station only
PARTY ID 002300005 the MMSI number of Suomenlinna Coast Guard Station
The Coast Guard station sends the following acknowledgement:
Format: SELECTIVE
Party ID: 273678951
Category: ROUTINE
Telecom 1: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel: 74
Transmitted: Ch 70
Party ID 273678951 = the MMSI number of Marlene
Format SELECTIVE = directed towards one station
The Coast Guard Station suggests:
Work channel 74
After this Marlene CONTINUES BY VOICE COMMUNICATION on channel 74:
Calling Finnish Coast Guard Suomenlinna, Finnish Coast Guard Suomenlinna,
This is Russian vessel Marlene, JAAA,
Russian vessel Marlene JAAA,
On VHF channel 74.
Over.
Russian Vessel Marlene JAAA,
This is Finnish Coast Guard Station
Suomenlinna,
Over.
Finnish Coast Guard station,
This is Russian yacht Marlene,
My position is: Latitude: 59° 56.9´ N Longitude : 024° 56.3´ E
I am in the approach channel passing Helsinki Lighthouse. I am proceeding to the Coast Guard
Station for passport control. REQUEST: Please give instructions to reach Suomenlinna Coast
Guard Station. Over.
Marlene,
This is Finnish Coast Guard.
INSTRUCTIONS: Proceed along the fairway. Pass Harmaja Lighthouse and proceed along the fairway
distance 1.6 miles. Take fairway depth 9.6, course 328°.
Proceed distance 0.8 miles. You can see the information on your starboard side.
I repeat: Proceed along the fairway. Pass Harmaja
Lighthouse and proceed along the fairway distance 1.6 miles. Take fairway depth 9.6, course 328°. Proceed
distance 0.8 miles. You can see the information on your starboard side. Over.
Finnish Coast Guard ,
This is Marlene.
UNDERSTOOD. I will proceed along the fairway and pass Harmaja Lighthouse. I will take fairway
depth 9.6, steering course 328°. I will proceed along the fairway distance 0.8 miles ahead. I can
see information sign on starboard side. THANK YOU AND OUT.
AS YOU NOTICED THE DSC CALL REPLACES THE INITIAL VOICE COMMUNICATION CALL
AND ANSWER ON CHANNEL 16. CHANGING TO A WORK CHANNEL ALSO HAPPENED VIA
DSC.
THUS A TRADITIONAL VOICE TRANSMISSION ON CHANNEL 16 DIFFERS SLIGHTLY IN THE INITIAL STAGE BUT RADIO PROCEDURE IS OTHERWISE THE SAME.
DSC DISTRESS COMMUNICATION
DSC DISTRESS INFORMATION:
A distress alert by Digital selective call should include the following information:
· the nature of call is DISTRESS
· MMSI number of vessel in distress
· position of vessel in distress in coordinates
· position at TIME
· nature of distress
· suggestion for follow up communication ( voice or text)
NOTE:
· A distress call is always addressed at all stations.
· Voice communication always takes place on channel 16.
NATURE OF DISTRESS
The DSC apparatus has a menu including the following choices for nature of distress:
· fire, explosion
· flooding
· collision
· grounding
· listing in danger of capsizing
· sinking
· disabled and adrift
· undesignated distress
· abandoning ship
· piracy/armed robbery attack
· man overboard
· EPIRB
EXAMPLE - DISTRESS CALL DSC
Area A1 on VHF
The DSC shows the following information:
Format: DISTRESS
Distress ID 230136780 (MMSI number of vessel)
Postion: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Transmitted: Ch 70
EXAMPLE - DISTRESS ACKNOWLEDGEMENT DSC
Area A1 on VHF
The Distress call is acknowledged by MRCC Turku:
The acknowledgement repeats the information in the Distress Call.
It is directed to and seen on the DSC apparatus by all ships in the vicinity.
Format: ALL SHIPS
From: 002301000
Category: DISTRESS
Telecom 1: DISTRESS ACKNOWLEDGEMENT
Distress ID: 230136780
Position: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SINPLEX)
Transmitted: Ch 70
AFTER THIS FOLLOWS VOICE COMMUNICATION ON CHANNEL 16
DISTRESS MESSAGE
MAYDAY
This is 230136780
VERA
CALL SIGN JULIETT ALFA BRAVO CHARLIE
POSITION: 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
DISTRESS ACKNOWLEDGEMENT
MAYDAY
VERA VERA VERA
Call sign Juliett Alfa Bravo Charlie
This is RESCUE CENTRE TURKU RESCUE CENTRE TURKU
RESCUE CENTRE TURKU
RECEIVED MAYDAY
Over
FOLLOWED BY A MAYDAY RELAY FROM THE RESCUE
CENTRE ON CHANNEL 16...
MAYDAY RELAY MAYDAY RELAY MAYDAY RELAY
ALL STATIONS ALL STATIONS ALL STATIONS
This is 002301000
Rescue Centre Turku Rescue Centre Turku Rescue Centre Turku
Following received from Vera Juliett Alfa Bravo Charlie at 1200 UTC on VHF channel 16 :
Begins
Mayday
This is Vera
Juliett Alfa Bravo Charlie
In position 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
Ends
Ships in area report to Rescue centre Turku
Over
DSC SAFETY COMMUNICATION
The following is an example of the MESSAGE STRUCTURE of a Safety Call with DSC by Turku
Radio. This call is seen by vessels in the area.
Format: All ships
From: MMSI NUMBER (002300230)
Category SAFETY
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted: Ch 70
It is followed by a safety call by voice communication sent by Turku Radio on VHF channel 16, so
that every vessel, even smaller ones without DSC will receive the warning. The safety message is
then read on the traffic channel:
SAFETY CALL ON CHANNEL 16:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING
PLEASE SWITCH TO TRAFFIC CHANNELS
SAFETY MESSAGE ON TRAFFIC CHANNEL:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING ….
DSC URGENCY COMMUNICATION
A vessel or a coast station can send an urgency call (Pan-Pan call) by DSC. The DSC call contains
information on which channel the voice communication will be read (Channel 16). The call can be
directed to all stations or directly to the nearest Maritime Rescue Centre.
A Pan-Pan message may be sent in, for example, the following situations:
· a person has fallen overboard and the ship needs help with search and rescue
· signals have been observed that might be distress signals
· when reporting on missing vessels
· if a person on board a vessel needs immediate medical assistance
· red rockets have been observed
EXAMPLE
The following is an example of an Urgency call to all stations by DSC:
A
Format ALL SHIPS
Category URGENCY
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted 70
A vessel can send an urgency call directly to the nearest Maritime Rescue Centre. Example of a
call sent to MRCC Turku:
B
Format SELECTIVE
Party ID 002301000
Category URGENCY
Telecom 1 TELEPHONY F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70
NOTE: when sending a DSC call to a Rescue Centre or Coast Station a vessel does not suggest
the working channel. This is done by the Coast Station or Rescue Centre.
distress channels. A ship equipped with a DSC apparatus can make a distress call by simply
pressing a button, which results in an automatic alarm signal at the maritime rescue centre nearest
to the vessel.
DSC can be used for all kinds of radio calls between ship-ship and ship-shore–ship. DSC calls are
made on channel 70, which means that any voice communication on this channel is not allowed.
The DSC call includes and shows the following information:
- Format or Type of Call
- Receiver or Party ID
- Call Category or Priority
- Telecommand
(follow-up radio communication)
- Working Channel
1. FORMAT OR TYPE OF CALL
One of the following are chosen on the DSC apparatus:
- distress alert / distress call in a distress
- all ships a call to all stations
- selective/individual a call to one station
(e.g. in routine calls)
- group a group of stations
- area / geographical call to stations in a
particular area
2. PARTY/RECEIVER ID (IDENTIFICATION)
The receiver of the call (Party ID) you can click either the Maritime Mobile Service Identity (MMSI)
number of the recediving station, a group call number or area call number. The MMSI always
contains nine digits.
Example of MMSI Number system:
MMSI Vessel Explanation
230252000 230 country code (Finland)
always three digits
252000 (ship’s number)
MMSI Coast Station Explanation
002301000 00 means coast station in general
230 country code (Finland)
number of particular coast station
1000 (Turku Maritime Rescue Coordination Centre)
3. CALL CATEGORY OR PRIORITY
- distress
- urgency
- safety
Routine Communication can be of two kinds:
- routine
- ship’s business
4. TELECOMMAND
This gives information on what kind of follow-up radio communication the sender wishes to have. It
also gives information on what kind of message the sender is giving. The most common
telecommand choices include:
- telephony G3E/F3E simplex
o voice communication on VHF
- distress acknowledgement
o request for acknowledgement of distress call
- distress relay alert
o request for relay of distress
- ship’s position
o request for a vessel’s position to be shown on DSC (routine call)
5. WORKING CHANNEL
The one who sends a DSC call can suggest a working channel for continued voice radio
communication.
NOTE: When a vessel is calling a coast station it does not suggest a working channel. The coast
station announces which radio channel to continue on.
ROUTINE COMMUNICATION WITH DSC CALL
EXAMPLE 1
A RADIO MESSAGE FOR SUOMENLINNA COAST GUARD STATION
COMPARE THE FOLLOWING TO THE EXAMPLES SENT WITHOUT DSC:
A Russian yacht Marlene is approaching the Finnish coast on its way to spend a holiday partly in
Helsinki and partly by sailing in the Finnish archipelago. According to European union laws a
foreign pleasure boat must report for passport control when she has entered the territorial waters
of one of the member states. The Marlene is a luxury yacht and is linked to GMDSS and has DSC.
It is 12.30 at Suomenlinna Coast Guard Station on a fine summer day.
The DSC at Suomenlinna starts signalling and shows the following message:
Format: SELECTIVE
Party ID: 002300005
Category ROUTINE
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70
NOTE: Marlene does not suggest a working channel. In communication between ship and coast
station, it is always the coast station that determines the choice of working channel.
SELECTIVE directed to a specific station only
PARTY ID 002300005 the MMSI number of Suomenlinna Coast Guard Station
The Coast Guard station sends the following acknowledgement:
Format: SELECTIVE
Party ID: 273678951
Category: ROUTINE
Telecom 1: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel: 74
Transmitted: Ch 70
Party ID 273678951 = the MMSI number of Marlene
Format SELECTIVE = directed towards one station
The Coast Guard Station suggests:
Work channel 74
After this Marlene CONTINUES BY VOICE COMMUNICATION on channel 74:
Calling Finnish Coast Guard Suomenlinna, Finnish Coast Guard Suomenlinna,
This is Russian vessel Marlene, JAAA,
Russian vessel Marlene JAAA,
On VHF channel 74.
Over.
Russian Vessel Marlene JAAA,
This is Finnish Coast Guard Station
Suomenlinna,
Over.
Finnish Coast Guard station,
This is Russian yacht Marlene,
My position is: Latitude: 59° 56.9´ N Longitude : 024° 56.3´ E
I am in the approach channel passing Helsinki Lighthouse. I am proceeding to the Coast Guard
Station for passport control. REQUEST: Please give instructions to reach Suomenlinna Coast
Guard Station. Over.
Marlene,
This is Finnish Coast Guard.
INSTRUCTIONS: Proceed along the fairway. Pass Harmaja Lighthouse and proceed along the fairway
distance 1.6 miles. Take fairway depth 9.6, course 328°.
Proceed distance 0.8 miles. You can see the information on your starboard side.
I repeat: Proceed along the fairway. Pass Harmaja
Lighthouse and proceed along the fairway distance 1.6 miles. Take fairway depth 9.6, course 328°. Proceed
distance 0.8 miles. You can see the information on your starboard side. Over.
Finnish Coast Guard ,
This is Marlene.
UNDERSTOOD. I will proceed along the fairway and pass Harmaja Lighthouse. I will take fairway
depth 9.6, steering course 328°. I will proceed along the fairway distance 0.8 miles ahead. I can
see information sign on starboard side. THANK YOU AND OUT.
AS YOU NOTICED THE DSC CALL REPLACES THE INITIAL VOICE COMMUNICATION CALL
AND ANSWER ON CHANNEL 16. CHANGING TO A WORK CHANNEL ALSO HAPPENED VIA
DSC.
THUS A TRADITIONAL VOICE TRANSMISSION ON CHANNEL 16 DIFFERS SLIGHTLY IN THE INITIAL STAGE BUT RADIO PROCEDURE IS OTHERWISE THE SAME.
DSC DISTRESS COMMUNICATION
DSC DISTRESS INFORMATION:
A distress alert by Digital selective call should include the following information:
· the nature of call is DISTRESS
· MMSI number of vessel in distress
· position of vessel in distress in coordinates
· position at TIME
· nature of distress
· suggestion for follow up communication ( voice or text)
NOTE:
· A distress call is always addressed at all stations.
· Voice communication always takes place on channel 16.
NATURE OF DISTRESS
The DSC apparatus has a menu including the following choices for nature of distress:
· fire, explosion
· flooding
· collision
· grounding
· listing in danger of capsizing
· sinking
· disabled and adrift
· undesignated distress
· abandoning ship
· piracy/armed robbery attack
· man overboard
· EPIRB
EXAMPLE - DISTRESS CALL DSC
Area A1 on VHF
The DSC shows the following information:
Format: DISTRESS
Distress ID 230136780 (MMSI number of vessel)
Postion: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Transmitted: Ch 70
EXAMPLE - DISTRESS ACKNOWLEDGEMENT DSC
Area A1 on VHF
The Distress call is acknowledged by MRCC Turku:
The acknowledgement repeats the information in the Distress Call.
It is directed to and seen on the DSC apparatus by all ships in the vicinity.
Format: ALL SHIPS
From: 002301000
Category: DISTRESS
Telecom 1: DISTRESS ACKNOWLEDGEMENT
Distress ID: 230136780
Position: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SINPLEX)
Transmitted: Ch 70
AFTER THIS FOLLOWS VOICE COMMUNICATION ON CHANNEL 16
DISTRESS MESSAGE
MAYDAY
This is 230136780
VERA
CALL SIGN JULIETT ALFA BRAVO CHARLIE
POSITION: 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
DISTRESS ACKNOWLEDGEMENT
MAYDAY
VERA VERA VERA
Call sign Juliett Alfa Bravo Charlie
This is RESCUE CENTRE TURKU RESCUE CENTRE TURKU
RESCUE CENTRE TURKU
RECEIVED MAYDAY
Over
FOLLOWED BY A MAYDAY RELAY FROM THE RESCUE
CENTRE ON CHANNEL 16...
MAYDAY RELAY MAYDAY RELAY MAYDAY RELAY
ALL STATIONS ALL STATIONS ALL STATIONS
This is 002301000
Rescue Centre Turku Rescue Centre Turku Rescue Centre Turku
Following received from Vera Juliett Alfa Bravo Charlie at 1200 UTC on VHF channel 16 :
Begins
Mayday
This is Vera
Juliett Alfa Bravo Charlie
In position 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
Ends
Ships in area report to Rescue centre Turku
Over
DSC SAFETY COMMUNICATION
The following is an example of the MESSAGE STRUCTURE of a Safety Call with DSC by Turku
Radio. This call is seen by vessels in the area.
Format: All ships
From: MMSI NUMBER (002300230)
Category SAFETY
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted: Ch 70
It is followed by a safety call by voice communication sent by Turku Radio on VHF channel 16, so
that every vessel, even smaller ones without DSC will receive the warning. The safety message is
then read on the traffic channel:
SAFETY CALL ON CHANNEL 16:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING
PLEASE SWITCH TO TRAFFIC CHANNELS
SAFETY MESSAGE ON TRAFFIC CHANNEL:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING ….
DSC URGENCY COMMUNICATION
A vessel or a coast station can send an urgency call (Pan-Pan call) by DSC. The DSC call contains
information on which channel the voice communication will be read (Channel 16). The call can be
directed to all stations or directly to the nearest Maritime Rescue Centre.
A Pan-Pan message may be sent in, for example, the following situations:
· a person has fallen overboard and the ship needs help with search and rescue
· signals have been observed that might be distress signals
· when reporting on missing vessels
· if a person on board a vessel needs immediate medical assistance
· red rockets have been observed
EXAMPLE
The following is an example of an Urgency call to all stations by DSC:
A
Format ALL SHIPS
Category URGENCY
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted 70
A vessel can send an urgency call directly to the nearest Maritime Rescue Centre. Example of a
call sent to MRCC Turku:
B
Format SELECTIVE
Party ID 002301000
Category URGENCY
Telecom 1 TELEPHONY F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70
NOTE: when sending a DSC call to a Rescue Centre or Coast Station a vessel does not suggest
the working channel. This is done by the Coast Station or Rescue Centre.
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